Wireless communication networks are widely deployed to provide communication services to both fixed and mobile devices. These services can include voice, data, video, messaging, web browsing, etc. Wireless communication has certain advantages, such as mobility, over wired communications for accessing a network. Various wireless standards have been adopted or proposed for wireless networks. These standards include 802.11 (WiFi), 802.16 (WiMAX), TIA-856 (which is also known as Evolution-Data Optimized—EV-DO), and long term evolution (LTE). Additional standards such as the fifth generation communication system (5G) are also being pursued.
Because of transmit power regulations, limited frequency allocations, interference, and/or radio wave propagation characteristics, it is desirable to implement the concept of device-to-device (D2D) communication for wireless devices (a.k.a., user equipment—UE.) D2D communication is a peer to peer link which does not use the entire cellular network infrastructure, but enables wireless devices to communicate directly with one another when they are in proximity to each other. One of the particular applications for D2D communications is for emergency services. D2D communication is also being investigated for applications where peer discovery is required for commercial applications in the presence of network support. Another use for D2D communication is to improve user data speed, and extend cellular coverage. However, wireless devices that are engaged in D2D communication can cause interference to other devices and/or base stations.
Overview
In an embodiment, a method of operating a communication system includes receiving, by a first wireless device, a first indicator corresponding to an access node transmission power. The first wireless device measures a second indicator corresponding to a received signal power from the access node. Based on the first indictor and the second indicator, an estimated signal strength of a transmission from the first wireless device arriving at the access node is calculated. Based on the estimated signal strength, a modulation and coding scheme (MCS) for use by the first wireless device to transmit directly to a second wireless device selected.
In an embodiment, a method of operating a communication system, includes configuring a first wireless device to communicate directly with a second wireless device. Uplink air-interface resources are scheduled among a plurality of wireless devices. The first wireless device receives a plurality of indicators of scheduled uplink air-interface resource. The pluralities of indicators are used to determine, by the first wireless device, at least one unscheduled uplink air-interface resource. The first wireless device communicates directly with the second wireless device using the at least one unscheduled uplink air-interface resource.
In an embodiment, a communication system comprises an access node to send indicators of scheduled uplink air-interface resources to a plurality of wireless devices. The plurality of wireless devices includes a first wireless device and a second wireless device. The first wireless device is configured to receive the indicators of scheduled uplink air-interface resources. Using these indicators, the first wireless device determines at least one unscheduled uplink air-interface resource that can be used by the first wireless device for device-to-device communication between the first wireless device and the second wireless device.